1966 427/390 one low cylinder

[John B.]

Hello all, i just did a compression test on my 427/390 stock. cylider 1 was 160, 5 was 145, all the rest were 180. Decided to do a leak down on 1,3,5. Cyl 1 was 8% rings, Cyl 3 8% rings and Cyl 5 was 6% rings. I was thinking 5 would have been worse with such a low compression. Does any one have any suggestions on what might be going on? The car sat for 18 years, i have ran it for 5 hours since.

Thanks

Mike

[Chris H.]

Re: 1966 427/390 one low cylinder

Mike does the motor use oil? Does it smoke? How do the plugs look? How does it run?

[John B.]

Re: 1966 427/390 one low cylinder

Chris, if it uses oil it is very little. No smoke. The plugs showed a rich burn. Runs and sounds great.

We hooked up the sun machine. We killed each cylinder. All had rpm drop except 5.

Mike

[Danny P.]

Re: 1966 427/390 one low cylinder

You have fresh oil if not do a oil change and filter and go for a long steady ride without stopping its been sitting for 18 years you may have a sticky ring and valve seat on # 5 cyl i would try that before taken anything apart then recheck Cyl. 5

[Mark E.]

Re: 1966 427/390 one low cylinder

You have fresh oil if not do a oil change and filter and go for a long steady ride without stopping its been sitting for 18 years you may have a sticky ring and valve seat on # 5 cyl i would try that before taken anything apart then recheck Cyl. 5

Agreed. If it runs okay, put some time on it and then recheck.

[John B.]

Re: 1966 427/390 one low cylinder

Thanks Danny and Mark. I will do that.
Mike